1. Field of Invention
The field of the currently claimed embodiments of this invention relates to systems and methods for measuring and monitoring uterine cervical activity indicative of labor.
2. Discussion of Related Art
Despite recent technological medical breakthroughs, the issue of diagnosing preterm labor has continued to plague the obstetric community. In order to fully understand the gravity of this need, it is important to recognize the regrettable outcomes and heavy costs related to preterm birth. Preterm births lead to 70% percent of neonatal morbidity and mortality, and cost the United States over $26.2 billion in 2005 alone. Currently there is no way of accurately detecting preterm labor, which often leads to preterm birth. Current detection methods, such as the commonly used tocodynamometer, lack the ability to detect critical cervical changes and uterine activity and/or contractions at early gestational ages. This prevents timely diagnosis and treatment of preterm labor. A method and device that detects preterm labor early in its course in patients is currently lacking.
Term delivery occurs between 37-42 weeks of gestation, whereas preterm delivery occurs between 20-37 weeks of gestation. Preterm delivery does not allow the fetus enough time to develop within the womb, resulting in severe short and long-term health issues for the neonate.
The unfortunate consequences of preterm delivery have encouraged the obstetric community to increase monitoring on those pregnancies with predetermined risk factors for preterm labor. These predetermined characteristics include factors such as extremes in maternal age (under 17 or over 35) and a history of preterm birth. Of the over 4 million births in the US each year, around 680,000 of those are considered at risk for preterm birth. These patients are monitored closely and required to make clinical visits as often as once a week. The main risk factors include: extremes in maternal age (<17 or >35); low socioeconomic status; stressful life situations; low weight gain; infection; cervical abnormalities or trauma; and history of preterm labor and birth.
The results of preterm delivery directly correlate to vast increases in medical costs. While current medical costs of term birth in the US average around $2,800 USD, the average cost of preterm delivery is $41,000 USD. This disparity in costs comprises a portion of the $26.2 billion dollars spent on preterm deliveries in 2005 alone.
All of the current methods employed to screen for preterm labor are ineffective, insufficient, or inaccurate. The tocodynamometer, used to detect contractions from the abdominal surface, is often unable to detect contractions and cervical changes at an early gestational age. Transvaginal ultrasound, while able to detect cervical changes even at very early gestational ages, cannot usually detect the contractions that are often present before these changes are evident. Symptomatic monitoring is insufficient because patients are most often not evaluated until the time for meaningful intervention has passed. Other tests such as infection screening only monitor one potential mechanism for labor initiation. Fetal fibronectin testing, while modestly accurate at predicting preterm labor, has a much higher negative predictive value.
Even with increased surveillance, the failings of current methods have led to an annual preterm birth rate of twelve percent in the United States. Failure to detect preterm labor early in its course means that by the time cervical changes have truly manifested, delivery can only be delayed by a few days. Additional difficulty arises in striking a balance between avoiding unnecessary intervention and making timely diagnosis and treatment. Therefore, there is a need for a device that accurately detects early signs of preterm labor in patients.